For Country/ Country & Western songs, I can recommend a couple of books:
Jumpin' Jim's Ukulele Country (ISBN 978-1-4234-0122-3, $14.95 USD) A Hal Leonard Corporation imprint, 6-3/4 x 10.5".
Try Amazon or Flea Market Music's site. Probably available cheaper some places. - There are 36 songs, and as with all of Jim Beloff's books, chord charts, anecdotes, and the first note sung is shown on each song.
The Easy Country Fake Book, Hal Leonard (ISBN 978-1-4234-3567-9, $19.95 USD) Not strictly Ukulele, but all in the key of C, has the melody line in musical notation, and the chord names - no chord diagrams. 176 songs. (Duplicates many from the Beloff book).
And finally one that has the full piano notation, along with guitar chord diagrams, also from an imprint of Hal Leonard Corporation:
Riders in the Sky present Classic Cowboy Songs. Shawnee Press. 12 Songs, (ISBN 978-1-4234-8655-8 $14.99 USD)
The last two are standard 9" x 12", and all three books are softcover.
I bought them from Music Village, on Union Ave in San Jose, CA.
Good Luck!
-Kurt